uapi/drm: add AMDGPU_HW_IP_VCN_DEC for decode CS

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

include/uapi/drm/amdgpu_drm.h

@@ -431,7 +431,8 @@ struct drm_amdgpu_gem_va {
 #define AMDGPU_HW_IP_UVD          3
 #define AMDGPU_HW_IP_VCE          4
 #define AMDGPU_HW_IP_UVD_ENC      5
-#define AMDGPU_HW_IP_NUM          6
+#define AMDGPU_HW_IP_VCN_DEC      6
+#define AMDGPU_HW_IP_NUM          7
 
 #define AMDGPU_HW_IP_INSTANCE_MAX_COUNT 1